A fluid is generally defined as any substance that can flow. Fluids encompass gases, liquids and combinations of gases and liquids. The field of fluid dynamics attempts to explain and characterize the behavior of fluids. Conventionally, such characterization has been through differential equations. The use of equations to simulate large and complex physical environments is difficult at least. Further, approximations inherent in processing the equations can cause significant errors.
A fundamental view of fluid dynamics is that fluids are comprised of particles. A corollary of this view is that behavior of the fluids can be explained from the behavior of the particles that make up the fluid. A vast majority of particles in the fluid are constantly in motion. The particles move undisturbed until they collide with other particles. Such a view of particles has given rise to a simulation approach in which the particles are viewed as traveling on a lattice and are processed individually. However, such a discrete system suffers several discreteness artifacts not found in real fluids.